A rotary, or reciprocating, machine can feature an enclosed internal mechanism that drives a shaft. In some cases, the shaft can pass through the housing of the machine on one or both ends. In such cases, a rotary shaft seal, sometimes referred to as a lip seal, can be disposed near an exit point to retain a lubricating fluid, such as oil or grease, in the housing as well as prevent ingress of contaminants, such as moisture and dust. The rotary shaft seal can have an outer diameter that provides a seal against the housing, and a sealing lip that provides a seal against the shaft. The sealing lip should exert a radial load on the shaft that provides sufficient sealing properties without excessive friction or wear.
There continues to exist a need for a rotary shaft seal having improved sealing properties.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the invention.